Isotachs

Isotachs are lines on a map that connect or denote areas of constant wind speed. This map shows the wind direction over east Asia.

http://tparc.cwb.gov.tw/data/model/Operation_CWB-NFS_45km/20080823/model.Operation_CWB-NFS_45km.200808231200.048_200hPa_Streamline_Isotach.gif